1. Field of the Invention
The present invention relates to an apparatus for automatically cleaning semiconductor wafers in a one-by-one manner (single wafer transfer system), including a wafer erection assembly, a brush cleaning bath, a plurality of wafer cleaning baths adapted to clean one wafer at a time by having each wafer steeped (e.g. soaked thoroughly) in a generally vertical orientation in the cleaning liquid, and a wafer handling apparatus consisting of a robot arm.
2. Description of the Prior Art
In the semiconductor device manufacturing technology, the impurities adhering to the surfaces of the semiconductor wafers are known to adversely affect the properties of the resulting semiconductor devices.
Therefore, a cleaning step is included in the semiconductor wafer manufacturing process. In the cleaning step, the wafers are cleaned in various methods which are classified broadly into two groups: mechanical cleaning methods and chemical cleaning methods.
The mechanical cleaning methods include the brushing method wherein the impurities adhering to the wafer surfaces are directly brushed off by means of appropriate brushes, the flushing method wherein the impurities are removed from the wafer surfaces as pressurized fluid from an injection nozzle is applied to the wafer locally or entirely, the ultrasonic cleaning method wherein the wafers are submerged in a liquid and the impurities are vibrated to detach from the wafer surfaces as ultrasonic waves are applied to the wafers.
The chemical cleaning methods include the methods wherein the impurities adhering to the surfaces of the wafers are removed as they are chemically dissolved by various chemicals and enzymes. There are other cases wherein a chemical cleaning method is combined with a mechanical cleaning method.